Cocoa Polyphenols

1
Cocoa Polyphenols

• Pennington Biomedical Research Center
  Division of Education
• Heli Roy, PhD
  Shanna
  Lundy, BS
  Phillip Brantley,
  PhD- Chief

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Overview

• An increasing body of epidemiologic evidence
  supports the concept that diets rich in fruits
  and vegetables promote health and attenuate, or
  delay, the onset of various diseases, including
  cardiovascular disease, cancer, and certain
  neurodegenerative disorders
• Epidemiologic data has linked these health
  benefits, at least in part, to the presence of
  certain flavonoids in fruits and vegetables

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Flavonoids

• Flavonoids are a group of polyphenolic compounds
  that occur widely in fruits, vegetables, tea, red
  wine, and chocolate
• Cocoa and chocolate products have the highest
  concentration of flavonoids among commonly
  consumed foods
• Over 10 percent of the weight of cocoa powder is
  flavonoids

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• Cocoa and chocolate products have been delicacies
  for hundreds of
  years
• Cocoa and chocolate have only recently have they
  been recognized as significant sources of
  phytochemicals, with healthful effects
• Cocoa and chocolate are among the most
  concentrated sources of the procyanidin
  flavonoids, catechin and epicatechin

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Chocolate Candy Consumption

• Americans eat a lot of chocolate in the form of
  candy (about 4.6 kg/year per person or 10
  pounds), but not as much as people in some
  northern European countries
• In Switzerland, the country with the highest
  chocolate consumption, it is estimated at 9.9
  kg/year (22 pounds) for each person
• Each candy bar contains about 210 calories, 13 g
  fat (7 of which is saturated), 23 g of
  carbohydrate, and 3 g of protein

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Flavonoids in Chocolate

• Chocolate and cocoa are unique in the type of
  flavonoids present
• The flavonoids in cocoa/chocolate, principally
  catechin and epicatechin, exist in long polymers
• They contain two, three, or up to ten of the
  catechin or epicatechin units linked, which is
  fairly distinctive, since most flavonoid-rich
  foods tend to have more catechins and
  epicatechins in dimers or trimers, not pentamers,
  hexamers, etc

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Flavonoids in Chocolate

• Also intriguing is the chemistry of flavonoids in
  cocoa which are really R-oligomers
• These structural characteristics of catechin and
  epicatechin represent the molecular basis for
  both their hydrogen-donating (radical-scavenging)
  properties and their metal-chelating antioxidant
  properties

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Flavonoid ContentIs Variable

• As with most plants, genetic and agronomic
  factors can markedly influence the contents of
  phytochemicals available at the time of harvest
• Postharvest handling also plays a critical role,
  because most cocoas undergo some fermentation
  steps, which subject flavonoids in the cocoa to
  heat and acidic conditions
• Subsequent processing steps, such as roasting and
  alkali treatment, can also reduce the flavonoid
  contents

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Flavonoid ContentIs Variable

• The actual recipe for the finished food or
  beverage product determines the amount of a
  given cocoa (and flavonoid) added.
• Depending on harvesting and processing
  procedures, as much as 90 of the
  flavonoids can be lost during processing

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Flavonoid Content

• Different types of chocolate contain varying
  antioxidant content
• In finished products, the amount of cocoa ranges
  from 7 to
  35 in milk chocolate and 30 to 80 in dark
  chocolate
• Consequently, the polyphenol content varies and
  is generally twice as high in dark
  than in milk chocolate
• Also interesting is the fact that white chocolate
  does not contain polyphenols

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Recent Studies

• Recently, Joe Vinson at the University of
  Scranton (PA), who has been studying total
  polyphenols in foods and beverages in the
  American diet, has found even higher levels of
  antioxidants in chocolate
• His studies have shown that on a weight basis,
  the concentration of polyphenols in milk
  chocolate is higher than in red wines and black
  or green teas. It is 20 times higher than in
  tomatoes, 2 times higher than in garlic, and over
  3 times higher than in grapes.

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Foods High in Antioxidants

• Beverages Tea (green and black), red
  wine, grape, tomato,
  orange, and apple juice
• Top 10 vegetables Garlic, kale, spinach,
  Brussels sprouts, alfalfa sprouts,
  broccoli flowers, beets,
  red bell peppers,
  onions, and corn
• Top 10 fruits Strawberry, plum,
  orange, red grapes, kiwi fruit,
  pink grapefruit, white grapes,
  banana, apple, tomato

In addition to chocolate, the following foods and
beverages are high in antioxidants
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• Numerous dietary intervention studies in humans
  and animals indicate that flavanol-rich foods and
  beverages might exert cardioprotective effects
  with respect to vascular function and platelet
  reactivity.

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• Antioxidant Capacity

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Atherogenesis

• Phenolic antioxidants have been shown to inhibit
  the oxidation of low-density lipoprotein (LDL)
  cholesterol, and mounting evidence suggests that
  it is the oxidized form of LDL that leads to the
  buildup of fatty plaques in arteries

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Atherogenesis

• Extracts of cocoa powder have also significantly
  inhibited LDL oxidation in vitro
• Kondo et. Al. reported that cocoa prolongs the
  lag time of LDL oxidation in a concentration-depen
  dent manner
• Cocoa phenols has shown to inhibit LDL oxidation
  by 75, whereas red wines only inhibit LDL
  oxidation by 37-65

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• Interestingly, cocoa powder and cocoa extracts
  have been shown to exhibit greater antioxidant
  capacity than many other flavanol-rich foods and
  food extracts, such as green and black tea, red
  wine, blueberry, garlic, and strawberry in vitro
• However, no long-term studies have evaluated the
  effects of cocoa polyphenol compounds on the
  oxidative modification of LDL in humans

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Short-term human studies

• Researchers set out to test whether or not these
  effects shown from in vitro studies could be seen
  in humans
• The levels of epicatechin and catechin were
  measured in humans at zero, one, two, and six
  hours following consumption of a single meal of
  chocolate
• The concentration in plasma levels peaked at
  about one hour however, by six hours the
  concentrations had almost disappeared from the
  plasma

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Same Effects in Humans?
Short-term human studies

• Indicated that cocoa flavonoids are absorbed and
  cleared from circulation
  relatively quickly
• Support the recommendations to consume several
  servings of fruit and vegetables per day as seen
  in a number of clinical trials with chocolate and
  other flavonoid-rich foods,
• Spacing intake of flavonoid-rich foods throughout
  the day could help to provide a
  continuous supply

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More studies

• Because there is six to seven times more
  epicatechin than catechin in cocoa/chocolate,
  most attention has focused on epicatechin in
  studies
• Consistent with in vitro studies, human studies
  indicate that small doses of epicatechin are
  effective
• There is a statistically significant increase in
  plasma antioxidant capacity and reduction in
  lipid peroxides following cocoa/chocolate
  consumption

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Benefits

• Epicatechin and other flavonoids not only have a
  direct antioxidant effect, but they may also have
  a sparing effect on other antioxidants such as
  Vitamins C and E

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Other Mechanisms

• Although flavanol-rich cocoa and chocolate have
  the potential to augment an individuals
  antioxidant defense system, there are other
  cellular mechanisms through which these
  flavanol-rich foods can affect cardiovascular
  health
• InflammationPlatelet aggregationNitric oxide
  (NO)-mediated endothelial changes

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• Inflammation

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• Atherosclerosis and heart failure, as well as
  risk factors such as hypertension and
  hypercholesterolemia, can activate several
  proinflammatory enzyme systems, such as xanthine
  oxidase, NADH/NADPH oxidase, and myeloperoxidase
• Once activated, these enzymes produce reactive
  oxygen species and other radicals that, as
  indicated above, can modify NO availability and
  LDL and contribute to endothelial dysfunction

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• Flavanol-rich cocoa liquor has been shown to
  stimulate NO production and to significantly
  reduce the activities of xanthine oxidase and
  myeloperoxidase after ethanol-induced oxidative
  stress
• In addition, cocoa flavanols and procyanidins may
  modulate other mediators of inflammation

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• Platelets

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• In addition to its influence on oxidative defense
  mechanisms, polyphenols seem to benefit
  cardiovascular health in other ways- through
  regulation of platelet reactivity
• Given the prominent role of platelets in the
  development and manifestation of acute myocardial
  infarction, stroke, and venous thromboembolism,
  antiplatelet strategies are an important
  consideration
• A modest decrease in platelet reactivity can be
  of value because it reduces the probability of
  clotting

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• In one study to determine whether cocoa inhibits
  platelet activation and function, subjects were
  given either water or 300 ml of cocoa that
  provided a very high amount of polyphenols
• During the six hour time period following intake
  of cocoa, there was a reduction in P-selectin,
  suggestive of less reactive platelets
• This is the same response that would be seen
  following intake of
  antiplatelet agents such as aspirin

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• Endothelium

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• Shear stress, ischemia and reperfusion,
  inflammation, and disease states, such as
  atherosclerosis, diabetes mellitus, and
  hypertension, can disrupt endothelial function
• This is associated with alterations in
  endothelium-derived regulatory mediators, an
  inability to regulate vascular tone, and an
  overall shift toward the prothrombotic state
• Possible that flavanols, by functioning as
  antioxidants, in addition to modulating
  prostacylin and leukotriene concentrations, can
  improve endothelial function through the
  prevention and possible reduction of oxidative
  damage

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Conclusions

• Although in vitro studies provide strong support
  for the hypothesis that flavanol-rich food
  consumption is associated with the reduced risk
  for vascular diseases, at this time the majority
  of studies that have been reported are in the
  form of short-term clinical trials
• The health benefits of these nutrients will best
  be determined from long-term, randomized,
  clinical trials

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References

• Keen C, et al. Dietary polyphenols and health
  Proceedings of the 1st international conference
  on polyphenols and health. Amer J Clin Nutr.
  2005. 811 298S-303S. Available at
  http//www.ajcn.org/cgi/content/full/81/1/298S
• Keen C. Chocolate Food as medicine/medicine as
  food. J Amer Coll of Nutr. 2001. 2090005
  436S-439S. Available at http//www.jacn.org/cgi/c
  ontent/full/20/suppl_5/436S
• Wan Y, et al. Effects of cocoa powder and dark
  chocolate on LDL oxidative susceptibility and
  prostaglandin concentrations in humans. Amer J
  Clin Nutr. 2001. 745 596-602. Available at
  http//www.ajcn.org/cgi/content/full/74/5/596

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References

• http//pubs.acs.org/hotartcl/tcaw/99/jul/chocolate
  .html
• http//sciweb.nybg.org/science2/pdfs/mb/chocolate.
  pdfsearch'alternative20therapies20sept/oct20c
  hocolate